Timber frame owner builder in NJ

[MossRoad]

Exciting times for you! Good luck with the project and thanks for sharing the fun. :thumbsup:

 

[emanaresi]

We will enclose with polyurethane sips. We also will be building a garage and a mudroom area connecting garage to house out of sips.

HVAC will be a geothermal open loop system. Our HVAC guy is very good but I think he doubts we will be as tight as we hope to be. He estimated equipment at about 6 tons, if I remember correctly, I think we will be able to downsize from that.

 

[BitChin1]

We will enclose with polyurethane sips. We also will be building a garage and a mudroom area connecting garage to house out of sips.

HVAC will be a geothermal open loop system. Our HVAC guy is very good but I think he doubts we will be as tight as we hope to be. He estimated equipment at about 6 tons, if I remember correctly, I think we will be able to downsize from that.

Be diligent here.
Ours originally spec'd 6T system along with the (2) 1T mini-splits we were adding in bonus room over garage and in loft area we did not want to run ducts to.
We finally agreed on a 3T system (pump-n-dump open loop). During recent cold spell we had no problem at all with most of the heating covered by the mini-split units (I think they would have been adequate by themselves but my wife wanted to keep door closed to bedroom areas and our basement was getting cool)
We did orient the house to take advantage of south sun exposure to high gain windows.

During last summer the mini-split from our loft provided most cooling (mid 90's)

I find that my Geo system does not operate very efficiently as it kicks on and off often unless we are at the extreme temps (hot/cold) and would have been ridiculous if we had gone with the 6T proposed.

My HVAC guy provided me the spreadsheets and SW he used to assess load - I made my own edits (vs the default values he uses) - then we "discussed" what system to install

We also used Poly SIPs for all except our small bump out for a pantry, the basement walkout walls and for our Bonus room over the garage - these areas were the primary locations we have air infiltration/thermal bridging (spray foam) - I think you will find the SIP rooms to be very well sealed (provided your installer pays attention to seams and plates - use EDPM gaskets as much as possible.

Our next biggest "leak" was our HRV - I have since sealed this unit and am not using it - in KS we get enough breaks in the weather that windows are opened and general traffic through doors, dryer etc provide air exchange. Have run into some excess humidity at sub-zero temps and we used bathroom exhaust to alleviate this.

 

[emanaresi]

Thanks, yes, I am doubtful that we will need the system to be as large as specified. I have agreed with the hvac installer to reevaluate before we install any equipment but after the sips have been installed. We will be either spray foaming or putting rigid foam on the basement walls, and I plan to condition the basement though it will not be finished until a later date. Total sq footage including the basement is about 5500 sq ft and there are quite a few cathedral areas. He provided me with the calcs that he did in order to apply for permits but I think there is room to make changes to further capture the airtightness and insulation value of the house. I do plan to use epdm gaskets on the sills and other areas that could become air infiltration ares.

I am surprised you decided to eliminate you hrv...it seems they are very strongly recomended due to tightness of the house. We do plan to have windows open during the more mid months, but probably 6 months of the year the house will be sealed up. We plan to install an ERV.

How big is your house? what did you do for windows and doors? CAn you provide me with your calcs? or maybe tell me what were the assumptions that were most "wrong" in your hvac contractor's calculations?

 

[emanaresi]

I forgot to say, the frame is eastern white pine, hand selected trees by our timber framer in Maine. He fell them, and sent them to his sawyer. It's been a fun process so far and we are just getting started.

The 3rd level "lofts" will just be a type of attic, we will probably use ships ladder style things to get up there. The one over our young daughter bedrooms we believe will be a nice pseudo private living area for them. A place to play fort when they are young and maybe a quiet reading area when they are a little older. Or maybe they'll have no interest in it and we'll have to find some other interesting use for it.

 

[tkappeler]

We will enclose with polyurethane sips. We also will be building a garage and a mudroom area connecting garage to house out of sips.

What is the R value of the SIPS? We are NJ also, same climate zone. We used Raycore's (closed cell poly with studs cast in them, foil vapor inside and out) 2x4 walls which are R26 and R45 for the ceilings. I was not sure how well it would work but it has exceeded my wildest dreams. Even on the coldest days a week ago (polar vortex ), it took over 6 hours for the temp inside to drop down 6 degrees. Our heater only runs 203 times per day with the high efficiency fireplace handling 1/2 of the house.

Looking forward to your updates.

 

[emanaresi]

The walls are 4.5" R28 roof 6.5" R40. I did read most of your thread. I'm glad the performance has been pleasing. I expect we will pay some performance price since we are building a masonry fireplace. Not a high efficiency, but we will pay the price to have the fire we want...

 

[BitChin1]

Thanks, yes, I am doubtful that we will need the system to be as large as specified. I have agreed with the hvac installer to reevaluate before we install any equipment but after the sips have been installed. We will be either spray foaming or putting rigid foam on the basement walls, and I plan to condition the basement though it will not be finished until a later date. Total sq footage including the basement is about 5500 sq ft and there are quite a few cathedral areas. He provided me with the calcs that he did in order to apply for permits but I think there is room to make changes to further capture the airtightness and insulation value of the house. I do plan to use epdm gaskets on the sills and other areas that could become air infiltration ares.

I am surprised you decided to eliminate you hrv...it seems they are very strongly recomended due to tightness of the house. We do plan to have windows open during the more mid months, but probably 6 months of the year the house will be sealed up. We plan to install an ERV.

How big is your house? what did you do for windows and doors? CAn you provide me with your calcs? or maybe tell me what were the assumptions that were most "wrong" in your hvac contractor's calculations?

As for the HRV/ERV - I would suggest you include it (in my case it was ~ $600, so best to have it and not use vs need it and not have it:thumbsup In my case I just found that it along with my bath fans and typical 30mph+ wind I was getting a wind tunnel effect between the HRV intake and my bath exhaust - after closing off the intake this has stopped and I am not noticing any ill affects of not running it - other than high humidity and your ERV won't reduce humidity much - the frame, along with other building materials hold quite a bit of moisture along with tight walls it does not escape from showers, cooking etc

My house is 1925sqft on main level, 2200sqft in basement, 500sqft bonus room (13,500ft^3 within the insulated boundary). main level great room is a large vault 29' to the peak(3 Bent at 1150sqft ~ 550sqft of which is a loft) - so slightly smaller than yours. also mine is a bit more "cubic" (less surface area) - my total volume was ~ 64,500ft^3 (I don't recall my surface area)

I will see if I can find the files we used for final calc (it was on his computer but I think he printed me a copy)

For windows I used Crestline from Menard's - inexpensive, but seem to work well. Main reason (other then cost) was they allowed me to special order my glazing for no extra cost!
I have 35 windows about half operable other half fixed. my glazing for most windows is their triple pane Zo-e-shield 8 low heat gain (standard in my area)
for 2 large main level picture frame (facing South) I used the double pane Zo-e-shield (could not provide 3 pane in this size) and for 4 large windows at 2nd level (above 10 tie beam) I used a special order Cardinal Glass 180 (I think it was) high solar gain
Doors I used Menards Mastercraft (planned to replace some time in the future but they were inexpensive and did not worry about damage during construction - so far they work well and look nice

Primary issue in the HVAC calcs was air infiltration rates - default was 7ACh! we did early test at 1.1ACh (blower door) w/o window/door insulation nor adjusting windows doors etc. Bonus room, pantry and basement did not yet have spray foam - so just the OSB and exterior WRB (sprayed/brushed Tremco - I really liked this product) providing air sealing.

They also assumed worst case air temp but that rarely occurs and then not for long periods.
Heat load they used default code minimum for window glazing and provide no credit for solar gain during heat calcs (my windows provide 80% of heat load over typical heating season) - we added a TF eyebrow to shade the high gain windows in summer

the other issue was that his load calc suggested we needed just under 5T, HVAC proposed 6T - "just to be safe" problem is this is safe from a "don't call me back" but it leads to inefficient operation.
My calculation showed I needed 2.25T but the 3T was smallest unit - I could have got by just with adding another mini-split in the basement and been fine
(but with 30% tax credit on the Geo system (all costs involved) I netted ~ $9k for the system cost of the geo (I used well to well open loop so not cost for tubing field or deep well etc)

to help with passive solar I used 1" concrete based with 3/4" stone for main floor - tiled our basement floor (with 2" R10 foam under slab) -


my SIPs ar R24 wall, R40 roof - basement is 2x8 stud with 2" closed cell, 5" open cell (so ~ R21 full wall) Bonus room was 3" closed cell with 9" open cell above 10', and 3" closed cell/R30 fiberglass batt elsewhere (foam guy ran out and I did not want to wait 3 days to close up ceiling)

 

[emanaresi]

Thanks for all of the insight, I will be sure to review the data he used for his calculations. I know it seems to be standard practice in the HVAC industry to upsize just to "be safe". We are pushing hard against that.

 

[jk96]

The walls are 4.5" R28 roof 6.5" R40. I did read most of your thread. I'm glad the performance has been pleasing. I expect we will pay some performance price since we are building a masonry fireplace. Not a high efficiency, but we will pay the price to have the fire we want...

I'm surprised your doing an open hearth. Doesn't an open hearth pull warm air out of the living space for combustion?

 

[emanaresi]

jk, yes, it does, but it also heats with radiant heat if done correctly. We are installing a rumford fireplace. It is one luxury that we really wanted even though it may cost a little bit in efficiency. Maybe its a decision we will regret, maybe not. Time will tell, I guess.

 

[jk96]

From what I read an open hearth on a 3000 sq ft home would cause an air exchange of up to 3 times per hour. Might want to make sure HVAC guy knows your doing an open hearth if you plan to use it frequently. I love the look but just could see anything but negatives when we were considering it.

 

[emanaresi]

There are ways to deal with it, one option is to provide makeup air near the fireplace. Good zoning on the hvac helps a lot too. The fact is, when you sit by a fire, you feel a lot warmer than the air temp on the thermostat in the same room may indicate. We are also building the entire masonry chimney within the home, so we will recapture a lot of the heat that is normally lost into the masonry and outside air. It is a thing that my wife and I have gone back and forth on a lot, but its something we really wanted and saw that it was a key part of our dream home.

The specification as I understand it is 1 cfm per sq inch of flue area. Our design calls for a 16" x16" flue, thats under 300cfm. Not insignificant, but not the end of the world. I have done a lot of research and was against the idea for a while, but the more I understand the entire proposition, the more I believe a lot of the naysayers get their info from the people trying to sell "efficient" fireplaces...

 

[dave1949]

Have you looked at other masonry fireplaces? The type with circulating flues passing through lots of masonry can be had with somewhat normal looking fireboxes. They aren't burned continuously though. They get fired once or twice daily then closed up. Those types of heaters are a warm mass that gently radiate heat for hours after burning. I suppose nothing really compares to an open fireplace for ambiance if that is your goal.

With a 16x16 flue, you ought to be able to cook in the thing. Have any plans for cooking cranes? :thumbsup:

 

[emanaresi]

We do plan to put a cooking crane in the fireplace. It will be a 42" rumford.

I am familiar with masonry heaters (with the serpentine flues). Like you said, it just doesn't satisfy what we are going for.

 

[BitChin1]

Hmm how well does this firebox seal when NOT in use?
Also what zone is your building site located and what is typical wind that will be hitting the house?
In a blower door test if this remains open you will see ~ 153,000CFH (in my house this would equal ~ 2.5ACH for this leakage alone - our 3T heat pump would likely have been a 5T to compensate)
I find at my house (SC KS) we get a lot of wind pressure which causes air leakage though any minor void - if you don't have this issue then the air leakage through the flow won't be that severe of an issue.

Anyway the only point is you are designing a very tight/efficient house otherwise and should attempt to maximize the efficiency related to this design element - that said you are building a HOME - it should match your personality and provide satisfaction in finished product
Some trade-offs are worth it as long as understood

 

[tkappeler]

We do plan to put a cooking crane in the fireplace. It will be a 42" rumford.

I am familiar with masonry heaters (with the serpentine flues). Like you said, it just doesn't satisfy what we are going for.

42" rumsford!!! Wow, that baby will be able to project some heat into the space. It sounds like you have considered it long and hard. It is your home and you have to live with it. The air exchanges/loss through the chimney not withstanding, I think you will be quite happy with the performance of your building envelope and be quite comfortable.

Keep the pictures coming.

 

[tkappeler]

HVAC will be a geothermal open loop system. Our HVAC guy is very good but I think he doubts we will be as tight as we hope to be. He estimated equipment at about 6 tons, if I remember correctly, I think we will be able to downsize from that.

I wish we could have afforded a geothermal system.

Are you in the pinelands? If so, how has it been in getting permits, etc through the pinelands commission?

 

[emanaresi]

We actually are not in a pinelands zone and don't have to worry about pinelands commission, otherwise we may have reconsidered the land purchase. That is not a process I want to deal with.

I think I am planning of installing a tight sealing flue damper in addition to a top damper. As I understand it, the top dampers do an excellent job of sealing a chimney when not in use. we are in climate zone 4. We do have wind here, but I think out in the pines it will be pretty well diffused. We are also only a few miles to the bay and our temps are pretty moderate most of the time due to the stabilizing factors of the bay.

See, I see things a little differently. I see that the fact that we are building a tight, high efficiency structures allows a little room to make the exceptions for the things we thing will make the house enjoyable (big windows, open fireplace, etc) I could just build the house as a cube with no windows and make a tremendously efficient walk in cooler, but thats not where me and my family wants to live. Keeping the thermostat in the living area set a little lower and burning a fire in the fireplace in the evening is something we are very much looking forward to. At first I tried to find a nice zero clearance that could capture the feeling and look we wanted, but it just isn't the same. There is one company that makes a zero clearance "high efficiency" rumford fireplace, when I looked at the price, I decided we would build a masonry rumford.

 

[BitChin1]

I wish we could have afforded a geothermal system.

Are you in the pinelands? If so, how has it been in getting permits, etc through the pinelands commission?

How deep is your water source? what type of drilling (sand/clay etc or granite?
In our area (understand this varies significantly) county allows pump and dump system with a number of requirements/constraints..
We needed two wells anyway (water for domestic use and a 2nd well for irrigation) so after tax credits our geo was less cost than a standard air source HP or an air conditioner/gas furnace
Anyone considering a Geo system - talk to several installers and evaluate all options (including foregoing the unit entirely in favor of several small min-splits)